The invention generally relates to the fields of computer systems and computer conferencing. More particularly, the invention is directed to methods and apparatus for efficiently utilizing multipoint conference bridge capacity.
Telephone conferencing systems have been available for many years. These systems have primarily focused on providing audio conferencing. A typical conference includes a group of individuals who are telephonically connected into a discussion by an operator at a central locality. In recent years, however, the addition of video capabilities as well as the use of multimedia applications has greatly increased the bandwidth required to establish a multipoint audio-video conference. Multimedia applications typically involve different application types such as control data, video, images, and audio, which are exchanged between the various participants in the multipoint videoconference.
A multipoint conference bridge (also known as a multipoint control unit, or MCU) is a logically centralized service that performs data combination and conference management, such as adding and dropping clients. The multipoint conference bridge has multiple physical ports, each of which can support a logical connection to a client to the conference. Each port of the bridge represents a certain amount of available digital signal processing (DSP) power in the conferencing fabric of the bridge. In the present discussion, only the audio portion of the conference is discussed for simplicity. Typically, the multipoint conference bridge accepts audio signals from each of the clients via respective logical connections, selects a signal to output (e.g., the strongest signal received from the clients) to all clients, and transmits this signal, thereby enabling multipoint communication.
However, a multipoint conference bridge always has a limited capacity. That is, a multipoint conference bridge may have four ports, which is sufficient only to support four conferees. A conventional approach used to increase the conference capacity is referred to as xe2x80x9cchaining.xe2x80x9d In chaining, multiple conference bridges are interconnected in order to increase the overall number of ports available to meet either anticipated or actual demand. As shown in FIG. 1A, two four-port multipoint conference bridges are shown chained together to increase the number of conferees able to participate in the conference to six. In particular, FIG. 1A shows a first four-port multipoint conference bridge 102 interconnected to a second four-port multipoint conference bridge 104 in support of a multipoint conference between six conferees (A, B, C, D, E, and F) that are logically connected to remaining ports of the bridges. Although the clients are shown connected to the ports of the bridges via direct lines, it should be noted that these direct lines indicate the logical connections, rather than the physical connections. Physically, the clients and bridges may each be connected to a network over which the logical connections are made as shown in FIG. 1A. This will also apply for FIG. 1B. Conventionally, this bridge-to-bridge interconnection is accomplished by connecting together one port from each conference bridge 102 and 104. By connecting the ports 102-4 and 104-1 for the dedicated bridge-to-bridge connection, the necessary number of ports is thus made available to connect the six conferees. Each multipoint conference bridge accepts audio signals from each of the clients connected via its logical connections. Each bridge then determines, e.g., the strongest signal received from its connected clients. Each bridge""s strongest signal is exchanged to the other bridge over ports 102-4 and 104-1. Each bridge selects the strongest of its strongest signal and the other bridge""s strongest signal to then be output to all clients. However, the total number of available ports for the two bridges is now reduced from a total of eight to six (a reduction of 25%), in order to provide for the shared multipoint conference having six conferees.
FIG. 1B illustrates the situation where an additional conferee G wishes to join the conference call with the conferees (A, B, C, D, E, and F). In order to accommodate the seventh conferee G, a third conference bridge 106 must be interconnected to the conference bridges 102 and 104. Since one additional port from bridge 104 must now be used to connect the bridge 104 to the bridge 106, one of the conferees coupled to bridge 104 must now be logically reconnected to the bridge 106. By way of example, the bridge 106 is connected to the bridge 104 by coupling the ports 106-1 and 104-4. However, the conferee F that was coupled to the port 104-4 must now be moved to the port 106-2. Even though chaining the conference bridges 102, 104, and 106 as shown in FIG. 1B provides the necessary number of increased ports to support the desired conference call, at least one port from each of conference bridges must be used to provide this bridge interconnection. This arrangement substantially reduces the number of ports from a maximum of 12 ports between three four-port bridges to only a maximum of 8 ports, a reduction of 33%.
Therefore, the user investment in providing multiple conference bridges for larger conferences is wasted to the extent that the dedicated bridge-to-bridge connection of ports results in the reduction of available ports for the conference clients. In addition to being expensive, additional conference bridges also increase the complexity of interconnects between the various bridges and any network, such as a LAN, to which the bridges are coupled.
Therefore, an improved method and apparatus for efficiently interconnecting multimedia conference bridges for a conference call are desirable.
Broadly speaking, the invention relates to an improved method, apparatus and computer system for reducing the number of interconnections between multimedia conference bridges in support of a multipoint conference. The multipoint conference is established by each multimedia conference bridge participating in the conference call determining which of its local clients is a local dominant client. In a preferred embodiment, audio signals are processed in such a way that resource intensive digital signal processing is not required to be performed. A global dominant client is then determined based upon a comparison of quantized values of all local dominant client""s signals against each other. The signal of the global dominant client is then transmitted, in either a multicast or unicast mode, to all clients participating in the conference call.
Various specific embodiments and other advantages of the present invention will discussed in further detail in the following detailed description in conjunction with the following drawings.